Cross-modal music-to-color associations were investigated in non-synesthetes and music-color synesthetes using 18 selections of orchestral music by Bach, Mozart, and Brahms. Six brief selections were chosen by each composer that varied in tempo (slow/medium/fast) and mode (major/minor). Non-synesthetes chose the 3 colors (from 37) that "went best/worst" with each selection. Synesthetes chose the 3 colors (from the same 37) that were most/least similar to the colors they experienced while listening to the same music. Non-synesthetes showed systematic patterns of cross-modal associations between musical features (tempo and mode) and the four dimensions of color appearance: high/low saturation, light/dark, blue/yellow, and red/green (Palmer, Schloss, Xu, & Prado-León, PNAS, under review). For example, faster music in the major mode was strongly associated with more saturated, lighter, yellower colors, whereas slower music in the minor mode was associated with less saturated (grayer), darker, bluer colors. Timbre-color synesthetes, whose sound-to-color associations are generally thought to be driven by low-level acoustic properties (as opposed to high-level musical ones), showed unexpectedly similar patterns in the colors they experienced while listening to the same selections of music. Both synesthetes and non-synesthetes showed clear evidence of emotional mediation, as indicated by reliable correlations between emotional ratings of the music and corresponding ratings of the colors they experienced/associated with the same music: e.g., the happiness/sadness of the music was correlated .91 with the happiness/sadness of the colors experienced by synesthetes and .95 with the happiness/sadness of the colors associated by non-synesthetes. Similar parallels were evident for the strength/weakness of the music and the strength/weakness of the colors experienced/associated with them (.61 for synesthetes; .96 for non-synesthetes), but not for angriness/calmness, for which non-synesthetes showed similarly high correlations (.89), but synesthetes did not (.33). Some emotions thus play a surprisingly powerful role in the colors experienced by timbre-color synesthetes.